[1] It is classified within the Parastylonuridae family and contains three species, S. arnoldi and S. beecheri from the Devonian of Pennsylvania, United States and S. spinipes from the Silurian of Kip Burn, Scotland.

[2] Stylonurella was a small stylonuroid, possessing a subquadrate prosoma with approximately the same length as width.

[3] Though one of the earliest described stylonurines, described shortly after the description of Stylonurus itself, it has no close relations to that genus.

For instance, the eyes of Stylonurus are located on the posterior half of the carapace and those of Stylonurella are on the anterior half.

Furthermore, there are noticeable differences between Stylonurella and its closest relative, Parastylonurus, for instance the widely different shapes of the carapaces (quadrate in Stylonurella and subrounded in Parastylonurus).